Method and system for remotely monitoring multiple medical parameters

ABSTRACT

The invention relates to a medical parameter monitoring device which allows the monitoring of a plurality of medical parameters from a remote location. The invention uses a central monitoring system which transmits and receives data parameters via RF from remote patient monitors. The monitoring systems utilizes a digital spread spectrum RF transceiver between the central monitoring system and the remote monitors. Forward error correcting, frequency hopping, and spread spectrum communications are employed to provide accurate trnsmission of data for a plurality of physiological parameters. Transmitted data can be automatically registered into storage int he central monitoring system.

“This is a continuation of copending application(s) Ser. No. 08/747,859filed on Nov. 13, 1996.

BACKGROUND OF THE INVENTION

This invention relates generally to medical parameter monitoring andmore particularly to monitoring multiple medical parameters of one ormore subjects from a remote location. One preferred embodiment of theinvention comprises a patient monitor and transceiver unit in one ormore parts, one unit for each of a plurality of patients; a remotedisplay/control device at a central monitoring system; and acommunications system between the patient units and the remotedisplay/control device.

Systems presently available for remote monitoring commonly employ eithera hardwired connection between the patient monitor and the remotedisplay/control device, or a unidirectional RF transmission from themonitor to remote display/control device only. Typically, analog signaldata is transmitted, although digital data can also be encoded andtransmitted. The remote display/control device generally supports anumber of patient monitors with transmitters, communicating withreceivers at the remote display/control device. The patient monitorsthemselves usually can only monitor one parameter (e.g., ECG), althoughsome systems permit the combination of multiple monitoring devices,sometimes with multiple transmitters per patient. The use ofunidirectional analog RF technology limits the patient sensor monitorsto performing pre-programmed tasks, with the only control being manualoperation of the patient monitor itself. The analog signal qualityreceived at the remote display/control unit tends to be dependent uponthe distance from the transmitter to the antenna(e); objects (buildingcomponents, movable objects, etc.) in between the transmitter andreceiver may compromise performance. Furthermore, transmissiontechnologies such as UHF, which employ a particular base frequency fordata transmission, face serious problems due to interference from othertransmission sources which happen to be transmitting at or near the samefrequency.

It is therefore an object of the invention to provide an improvedmedical monitoring system including a patient monitor and a centralmonitoring system using bidirectional data transmission.

It is a farther object of the invention to provide a novel medicalmonitoring system that enables dynamic control of remote monitoringsimultaneously with medical parameter and/or waveform data acquisition.

It is yet another object of the invention to provide an improved medicalmonitoring system which can receive and control a plurality of medicalparameters and/or waveforms being monitored at remote locations.

It is a further object of the invention to provide a component which canbe used therewith to automatically acquire and store data pertaining tovarious physiological parameters.

It is yet another object of the invention to provide a telemetry systemwhich enables automatic acceptance of patient data and immediateanalysis thereof and/or comparison with previously-acquired data.

It is another object of the present invention to use RF communicationand automatic registration of critical data, as well as in combinationwith forward error correcting, frequency hopping, spread spectrumtechnology, to provide significantly improved results which aresurprising and unexpected in view of the prior art.

Other objects, features and advantages of the present invention will beapparent from the following description of the preferred embodiments,taken in conjunction with the accompanying drawings described belowwherein like components have like numerals throughout several views.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a medical monitoring system constructed inaccordance with one form of the invention.

FIG. 2 is a block diagram showing one preferred embodiment of a patientmonitor of the present invention;

FIG. 3 is a schematic representation of the pneumatic function of anon-invasive blood pressure component of the type which can be used witha preferred embodiment of the invention;

FIG. 4 is a block diagram illustrating software configurations and/ornetworks of one type which can be used in accordance with the systemand/or method of this invention; and

FIG. 5 is a block diagram showing a medical monitoring systemconstructed in accordance with one form of the invention.

SUMMARY OF THE INVENTION

Referring to the figures and more particularly to FIG. 1, a monitoringsystem constructed in accordance with one form of the invention is showngenerally at 10. This preferred embodiment of the invention transmitsremotely monitored digital medical data using bidirectional, preferablyspread-spectrum RF transmission of digital data which can includeforward error correction. Bidirectional transmission permits a remotedisplay/control device 12 of a central monitoring system system 14 tocontrol the monitoring process completely, including selection ofmedical parameters and/or waveforms to be determined by a patientmonitor 16 borne by the patient or located at bedside. This ability tocontrol the patient monitor 16 is important in supporting a broad rangeof different types of patient monitors 16, from small ambulatorymonitoring devices to large bedside monitors with a broad assortment ofmonitoring capabilities. By permitting dynamic configuration, the mix ofpatient monitors 16 can change to suit the current patient population. Afurther feature of this preferred embodiment is the ability to identifythe location of a patient being monitored by the system. Additionally,these bidirectional capabilities enable messages to be sent directlyfrom the central monitoring system 14 or devices coupled thereto to thepatient monitor 16 or devices coupled thereto. For example, a nurse canrespond to a call signal initiated by the patient by sending a messagefrom the central monitoring system 14 to an alphanumeric display atbedside. Methods for direct digital signal formation from input signalsproduced by a sensor device can be used with preferred embodiments ofthe invention, and U.S. patent application Ser. No. 08/683,617 isincorporated by reference herein in its entirety for further detailsregarding such digital signal formation techniques and its incorporationas part of a combination of elements.

The present invention also offers automatic patent physiologicalregistration of the patients through RF communication once the patientmonitors 16 are connected to the patient as described below. Thisfacilitates an immediate acquisition of any and all parameters and/orwaveforms associated with the central monitoring system which may beapplicable to the respective patient. These parameters and/or waveformscan comprise ECG, NIBP, SpO₂, respiration, temperature, four invasivelines, alarms, remote recording, and transmitter ID number, as well asother relevant patient information. Further, the bidirectionalcapabilities of the present invention allow selection of whichparameters or waveforms to monitor with patient monitors 16 from theremote, central monitoring system 14. Additionally, the data samplingrates and all other monitoring parameters can be changed remotely usingthe central monitoring system 14.

As mentioned above and as shown in the figures, the present inventioncan include an automated data acquisition and/or storage component. Sucha component, in its various embodiments, can without limitation beincorporated for use in conjunction with the clinical analysis oftransmitted data. This component accommodates automatic patientadmission and facilitates the immediate transfer/receipt of data to acentral central monitoring system. When a patient is connected to atelemetry transmitter, clinical data is at once available and can beanalyzed for various diagnostic purposes. This aspect of the inventioncan allow for the immediate clinical presentation and analysis of ECG,NIBP, SO₂, as well as other pertinent information. This automatedcomponent is preferably located in the central monitoring system 14although it can be located in or coupled to one or more of the patientmonitors 16 or other devices.

By way of comparison, the prior art-affording a telemetry interfacelimited to one or two parameters-is somewhat restrictive in that acentral monitoring system must wait for manual acceptance of datatransmitted to a central station. For example, an end user of the priorart must manually instruct a central receiving location to learn atransmitted ECG pattern before such data is available for furthercomparison and analysis. The acceptance delay inherent to the prior artcan cause valuable clinical data to be irretrievably lost. In otherinstances, with manual acquisition and storage of data, substantialdelays may occur before the data is available for evaluation. However,with the present invention, once the patient monitor 16 is activated,data can be acquired, stored and evaluated upon transmission/reception.For example, ECG data can be automatically stored and evaluated forcomparison to future output ECG data by a central monitoring system 16.

Referring, in part, to the figures, the data acquisition/storagecomponent of this invention can, alternatively, be described in relationto other invention components. Data describing various physiologicalparameters can be displayed on conventional computer display monitorsinterfaced with the central monitoring system 14 or other receivingdevice hardwired or otherwise communicating with the central monitoringsystem 14. The central monitoring system 14 preferably includes aprinter, a computer monitor, a CPU such as a conventional personalcomputer and a conventional RF transmitter, an RF receiver or anintegral RF transceiver. Automatic physiological registration of thepatients is afforded trough RF communication once the patient monitor 16is connected to a patient. This facilitates an immediate acquisition ofany and all parameters associated with a host monitor and applicable toa respective patient. Such parameters can include, but are not limitedto ECG, NIBP, SpO₂, respiration and temperature. Comprehensive trendingof such parameters over time is available. A 24-hour trending capabilityis preferred. The trending can involve single or multiple parameters andis especially useful for cardiorespiratory patients, or those with othercardiovascular abnormalities. Invasive lines, alarms, remote recordingand transmitter identification can, without limitation, also beincorporated.

While a variety of spectrums and telemetry techniques can be usedsatisfactorily, preferably a transmitted event signal is digitizedinside a host monitor and transmitted via RF communication using ISMband technology in conjunction with forward correcting, frequencyhopping, spread spectrum technology, to the central monitoring system 14or other component. The event can be a 36-second stored event chosen tobracket the time of the event. If so, the central receiving centralmonitoring system can provide a display six seconds before the event,six seconds during the event, and for 24 seconds following the event.Other display sequences are possible. The station can also, as needed,incorporate disk drive technology, preferably a 1.44 MB floppy diskdrive, which enables a clinician to store and/or retrieve patient data.In preferred embodiments of this sort the central central monitoringsystem can analyze and store up to 120 events. Such events can becataloged in an appropriate manner for easy retrieval such that arunning total of events can be reviewed and, as needed, compared tothose events not yet reviewed. Events can also be reprinted, stored on afloppy disk or deleted at any time according to standard operatingprocedure.

As indicated above, the present invention allows transmission of severalphysiological parameters simultaneously, through hardwire, RF or othercommunication in contrast to the prior art where simultaneoustransmission is limited. The present invention overcomes such alimitation, without degradation of signal and without a slowdown insystem function. Simultaneous transmission, alone or in conjunction withother components of the present invention, permits maintenancemonitoring capabilities during the transport of the patient. Forinstance, a clinician using the present invention is able to transportthe patient in such a way as to continuously monitor both invasive andnon-invasive physiological parameters. By way of comparison, an end userof the prior art would necessarily disconnect the patient from a hostmonitor and reconnect that patient to a second monitor, one especiallybuilt for transporting the patient. The advance represented by thepresent invention assists the administration of health care. Continued,uninterrupted monitoring of all parameters and/or waveforms, bothinvasive and non-invasive, is possible throughout the transport andcompletion of a subsequent procedure. Furthermore, if hemodynamicmonitoring circuits are involved, dispensing with the need to disconnecta patient will decrease the inclement risk of contamination. The patientcan be transported immediately and when required, without delay due tochanges in monitoring requirements. The continued, uninterruptedmonitoring of all parameters and waveforms can be accomplished inseveral ways.

In accordance with one preferred embodiment of the invention, aplurality of the central monitoring systems 14 are located throughout afacility and can communicate with one another via hardwire, RF or othercommunication methods. Transfer of a patient from one central monitoringsystem 14 to another can be accomplished either by manually initiating atransfer function at the initiating central monitoring system 14, or canbe accomplished automatically by sensing when a patient enters a zoneallocated to another central monitoring system 14. The manual transfermethod has the advantage of requiring personnel to consciously executethe command and monitor the results of the transfer. In this way, nopatient is inadvertently lost by the system. Appropriate confirmationcan be provided to ensure the transfer has been effectively completed.In accordance with the automatic transfer method, the fields of thecentral monitoring system 14 preferably overlap so that continuousmonitoring from a central location can take place.

Alternatively, monitoring can be switched from central monitoring by thecentral monitoring system 14 to the patient monitors 16 in transit. Whena transfer is completed, the patient can be automatically registeredinto the appropriate central monitoring system 14 to which the patientis being transferred. Communication between the central monitoringsystem 14 enable historical patient data to be transferred during orsubsequent to the transfer procedure.

While a variety of technique can be used, preferably the ISM frequencyband is divided into a number of discrete channels. Each of the centralmonitoring system 14 can then operate on its own channel.

In accordance with another preferred embodiment of the invention, thecentral monitoring systems 14 can be accessed from another remotelocation, such as a lounge and interrogation of certain patientparameters and waveforms can be initiated. In this way, nurses or otherpersonnel can monitor a patient while performing activities in locationsother than a central monitoring system.

A preferred embodiment of the present invention is as presented throughthe multiple parameter telemetry system available under the MPTtrademark from Criticare Systems, Inc. of Waukesha, Wis. Thenon-invasive blood pressure component of this embodiment utilizesoscillometric measurement upon inflation. It can average less than 40seconds, standard adult cuff. Various automatic measurement cycles areavailable. Continuous readings are available for up to five minutes.Operative pressures range from 30-300 mm Hg for adults and 20-150 mm Hgfor neonates. Such a component typically has an accuracy of +/−2% or+/−2 mm Hg over the full range of pressures. The pulse oximetrycomponent has a range of 0-99%, with a resolution of 1%. Typically,accuracy is +/−2% (70-99%) and +/−3% (50-69%). Dual wavelength LED is apreferred method of operation. The ECG component utilizes band widths of0.05-100 Hz and 0.5-40 Hz. Heart (pulse) rate is measurable over a rangeof 20-300 beats per minutes, with updates available from beat to beat.Such a component is accurate to +/−1 BPM or 1% (the larger)—ECG and/or+/−2 BPM or 2% (the larger)—SpO₂ and NIBP. Other parameters andwaveforms that can be monitored include invasive blood pressure monitorsat multiple sites, respiration monitors, body temperature monitors,inspired and expired CO₂ levels in inspired and expired air, O₂ levelsin inspired and expired air, anesthetic levels including nitrous oxidelevels in inspired and expired air. It will be apparent to one ofordinary skill in the art that the patient monitors 16 can include anynumber of conventional monitoring devices for monitoring theseparameters and waveforms. With respect to particular RF specifications,the receiver frequency and transmitter frequency can be ISM 902-928 MHzalthough any legally permissible frequency range can be used. Aninternal antenna is preferably used with the frequency hopping spectrumspreading techniques which are well known in the art

In accordance with another preferred embodiment of the invention, anexternal RF modem can be used with conventional bedside monitors such asthose commercially available from the assignee of the present invention.The external RF modem can be used to communicate with the centralmonitoring system 14 instead of requiring a specially configured patientmonitor 16 including RF transceiver technology.

While preferred embodiments of the invention have been shown anddescribed, it will be clear to those skilled in the art that variouschanges and modifications can be made without departing from theinvention in its broader aspects as set forth in the claims providedhereinafter.

What is claimed is:
 1. A method of monitoring a plurality ofphysiological parameters representing the condition of a patient, saidmethod comprising the steps of: coupling a patient monitor having atransceiver to said patient to continuously monitor at least one of saidphysiological parameters; transmitting a select data signal from acentral monitoring system to the patient monitor to select at least oneof said physiological parameters to monitor at the patient monitor;transmitting a parameter data signal corresponding to a continuous,uninterrupted representation of said selected physiological parametersfrom said patient monitor to said central monitoring system; anddisplaying said continuous, uninterrupted representation of said atleast one selected physiological parameter on a display of said centralmonitoring system.
 2. The method as defined in claim 1, wherein saidselected physiological parameter includes at least one of bloodpressure, heart rate, SpO₂, respiration and ECG.
 3. The method asdefined in claim 1, wherein transmitting said parameter data signalincludes simultaneously transmitting a representation of a plurality ofphysiological parameters.
 4. The method as defined in claim 3, wherein aplurality of physiological parameters consists of ECG, NIBP, SpO₂,respiration, temperature, and four invasive lines.
 5. The method asdefined in claim 1, further comprising the step of storing at least onetime bracketed event.
 6. The method as defined in claim 5, furthercomprising the steps of storing a plurality of said time bracketedevents, categorizing the plurality of time bracketed events, andcompiling a running total of events for review.
 7. The method as definedin claim 1, further comprising the step of trending a plurality ofphysiological parameters over time.
 8. The method as defined in claim 1,further comprising the step of selecting a date sampling rate for thepatient monitor at the central monitoring system.
 9. The method asdefined in claim 1, wherein transmissions to and from the centralmonitoring system comprise spread-spectrum digital transmissions in theISM band.
 10. The method as defined in claim 1, further comprising thestep of identifying the location of the patient at the centralmonitoring system.
 11. The method as defined in claim 1, furthercomprising the step of dynamically selecting at least one waveformparameter to monitor at the patient monitor and to be transmitted to anddisplayed on the display of said central monitoring system.
 12. A systemfor monitoring physiological data representing the condition of apatient, said system comprising: sensors for monitoring blood pressure,pulse rate, blood oxygen concentration and electrocardiographicinformation to provide the physiological data; a patient monitor coupledto the sensors for continuous, uninterrupted collection of thephysiological data; a central monitoring system for storage, analysis,and display of continuous, uninterrupted physiological data collected bysaid patient monitor, the central monitoring system including atransmitter for transmitting a select data signal to select at least onephysiological parameter to be monitored at said patient monitor; thepatient monitor including a radio-frequency transmitter for transmittingsaid physiological data from said monitor to said central monitoringsystem.
 13. The system of claim 12 wherein said patient monitor isinterfaced with at least one additional central monitoring system forcontinuous, uninterrupted bi-directional communication.
 14. The systemof claim 13 wherein said patient monitor has a storage component forstoring physiological data, said component operative upon cessation oftransmittance from said central monitoring system and beforetransmittance to said additional central monitoring system.
 15. A systemfor monitoring physiological data representing the condition of apatient, said system comprising; sensors for monitoring blood pressure,pulse rate, blood oxygen concentration and electrocardiographicinformation to provide the physiological data; a patient monitor coupledto the sensors for continuous, uninterrupted collection of thephysiological data; a central monitoring system for storage, analysis,and display of continuous, uninterrupted physiological data collected bysaid patient monitor, the central monitoring system including atransmitter for transmitting a select data signal to select a pluralityof physiological parameters to be monitored at said patient monitor; thepatient monitor including a radio-frequency transmitter for transmittingphysiological data representing the selected plurality of physiologicalparameters from said monitor to said central monitoring system.